Telephone system.



No. 814,830. PATENTED MAR. 13, 1906.

L. W. CARROLL.

TELEPHONE SYSTEM. APPLIOATION FILED MAE.2 4.1903.

' UNIT D srrrrns PATENT orrron.

LOUIS w, CARROLL, or ANAMosA, IOWA, ASSIGNOR TO THE KELLOGG ISWI-TOHBOARD a SUPPLY (JOM1ANY,-OF omo eo, ILLINOIS.

. 'TELLEPHONE SYSYTEIM.

Specifi oation of Letters Patent. Application filed March 24,1903. sextant. 149,265. y

Patented March 13, 1906.

To all whom it may concern:

Be it known that I, LOUIS W. CARROLL, a citizen of the United States,and a resident of Anamosa, county of Jones, and State ofilowa, have invented certain new and useful Improvements in Telephone Systems, of which i the central exchange, means also being providedfor cutting anyfof'the telephones cfi from its companions on the same circuit and required of the operator at the exchange. if the local business of a party-line is very conconnecting it for signaling purposes with the central exchange. j

In systems of this kind it frequently happens that the users of the so'iveral telephones of the line have occasion to have considerable business with each other, and when; as has heretofore been the practice, a call from one of these telephones to another also calls the central exchange unnecessary service is siderable, so that these useless calls upon the central exchange become numerous, the operator naturally becomes indifferent to them,

so that when a signal is really intended for her it may have to be repeated several times A further objection to employed. I, y

A further object of the present invention is to provide mean's forcalling thecentral exchange from any of the telephones of the circuit Withoutsignaling to the companion instruments. p

These several objects areattained in the mechanism and system of wiring, as hereinafter descr bed and as convent1onally shown in the accompanying drawing.

The illustration represents at 10 a central exchange, and at 11 12 two telephones of a party-circuit in which the line-wires are shown at 13 14. While but twotelephones are represented, it will be understood, of course, that the invention is applicable to systems in which a larger number are employed,, i

type and need not be described in detail. Each is provided with a transmitter 15, a receiver 16, a call-bell 17, and a magneto-generator for signaling purposes, (shown at 18.)

By means of a spring-closed switch 19 the generator of each telephone is normally The telephones represented are of the usual bridged into the linecircuitthat of the telephone 11 through thewvires 21 and 24 and of the telephone 12 through the wires 25 and 28; The line-circuit is normally open at the exchange end, being provided with a jacksocket for receiving the circuit-closing plug.

transmitted through the wires 21, 13, and 22 to the call-b01117 of the telephone 12, the circuit being completed through the wire 23 to the line-wirgi'l z, and thence through the wire 24 back tc'i the generator 18 of the telephone 11. The circuit 13 14 being open at the central exchange, no signal is given there.

jiisignal emanating frorn the generator 18 of thetelephonem islcommunicated to thePbelI 17 of the telephone 11 through the wire 25, the line'wire 13, the wires 21 and 26, return ing through the wire 27, the line-wire 14, and the wire 28. As before, no signal is given at the central exchange, because of the open line-circuit at that point.

In order to signal to the central exchange from either of the telephones, the switch 19 is, thrown in opposition to its spring, so as to cut the generator 011' from the wire 24 01128 and connect it into the ground-wire 29 or 30. If now the magneto-generator of either telephonesay 12-be operated, the circuit is led through the wire 25, the line-wire 13, the wire 32 leading therefrom to'the drop-signal device 31 at the central exchange, and thence to the ground wire 33, the return being through the ground wire 30. This circuit does not lead to the telephone 11. Similarly,

A call-signal fromthe telephone 11 is the central exchange may be called from the ll claim my invention- 3.. In a telephone system, in combination, central or exchange station, a metallic circuit leading therefrom. and being normally open at said station, a plurality of telephones bridged into the circuit, each telephone havingan annunciator and asignaling-generator, a normally open grounded connection for each signalin -generator, and an annunciator at the centr or exchange station located in a grounded connection of one side of the metallic circuit. 1

In a telephone system, in combination, a central or exchange station, a metallic circuit leading therefrom and being normally open at said station, a plurality of telephones bridged into the circuit, each telephone having an am'iunciator and asignaling-gencrator, a grounded connection for each signalinggencratcr, a switch connecting the return side oi the generator alternately With the grounded connection and with the metallic ci *euit, and an annunciator at the central or exchange station located in a grounded connection of one side of the metallic circuit.

3; in a telephone system, in combination, a central station, a plurality of substations, a metallic circuit normally closed between substations and normally open at the central station, an annunciator at the central station, a grounded connection from one branch of the metallic circuit through the annunciator, and means for grounding the circuit at each substation independently of the telcphone instrument.

4. In a telephone system, in combination, a central station and a plurality "of substations, a metallic circuit connecting all of such stations, a grounded branch of the circuit at the central station containing an annunciator, a dynamo signaling device in tl'iccircuit, and means for grounding one terminal of the dynamo.

5. In a telephone system, in combination, a central station, a metallic circuit normally open at the central station, a plurality of substations on the circuit, a grounded branch of the circuit at the central station, an annuuciator in such branch, a signaling device normally inthe metallic circuit at each substation, andmeansindependent of the telephone i instrument for grounding one terminal of the sign aling device.

6. In a telephone system, in combination, a central station, a metallic circuit normally open at the central station, a normally closed ground for one branch of such circuit at the central station, a plurality of substations each bridged into the metallic circuit, a signaling device in the local circuit of each substation, and means in connection with each signaling device for grounding the terminal thereof which is not connected with the normally grounded branch of the metallic circuit.

LOUIS W. (JARROIIIIJ. Witnesses VVMI. A. HALE, H. D. Mrnrcn. 

